HARQ-ACK Mapping for Semi-Persistent Downlink in Flexible TDD

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Solution Overview

Problem

Existing radio networks face challenges in efficiently managing HARQ-ACK feedback due to conflicts with flexible TDD configurations, leading to increased latency and signaling overhead.

Innovation Solution

A flexible feedback mechanism using a set of offset indicators to determine uplink radio resources for HARQ-ACK transmission, independent of SPS configuration or TDD frame structure, allowing for dynamic mapping and reduction of signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If HARQ-ACK feedback is transmitted according to fixed timing relative to SPS downlink data, then the feedback timing is predictable and simple to manage, but conflicts arise with flexible TDD configurations causing increased latency and signaling overhead

Engineering Contradiction:

Improveflexibility in TDD configurationVSAvoidlatency in HARQ-ACK feedback

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the HARQ-ACK feedback timing dynamic rather than fixed. The UE determines the uplink radio resource for HARQ-ACK feedback based on the actual TDD configuration and available uplink slots, allowing the system to adapt to flexible TDD patterns while minimizing latency. This resolves the contradiction by enabling both adaptability to TDD configurations and reduced latency through dynamic timing adjustment.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the timing parameter for HARQ-ACK feedback from a fixed offset to a dynamically determined value based on TDD configuration and uplink availability. By changing this parameter adaptively, the system achieves both flexibility in handling different TDD configurations and optimization of feedback latency, resolving the technical contradiction between adaptability and time loss.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple backup timing values are maintained for HARQ-ACK feedback, then conflict resolution capability is improved, but signaling overhead and device complexity increase

Engineering Contradiction:

ImproveHARQ-ACK feedback delivery reliabilityVSAvoidcomplexity of timing management

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by enabling the UE to autonomously determine the appropriate uplink radio resource for HARQ-ACK feedback based on the TDD configuration and a pre-configured set of offset indicators. The UE independently resolves timing conflicts without requiring complex network signaling or multiple backup timing values, thereby improving reliability while reducing device complexity and signaling overhead.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the timing conflict resolution logic from the network side and places it on the UE side. By providing a set of offset indicators and an iteration scheme, the network enables the UE to independently determine valid uplink resources, removing the need for the network to manage multiple backup timing values and reducing overall system complexity while maintaining reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If HARQ-ACK feedback is transmitted as early as possible, then latency is reduced and retransmission opportunities are increased, but control overhead increases due to conflict management

Engineering Contradiction:

Improvefeedback transmission efficiencyVSAvoidcontrol signaling overhead

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent introduces an intermediary mechanism in the form of a pre-configured set of offset indicators and an iteration scheme. This intermediary enables the UE to determine valid uplink resources autonomously without requiring complex real-time signaling from the network, thereby reducing control overhead while maintaining early feedback transmission and high productivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of operation

If the k1 set is coupled to SPS configuration and TDD frame structure, then timing alignment is simplified, but flexibility is reduced when SPS or TDD configuration changes

Engineering Contradiction:

Improvesimplicity of timing configurationVSAvoidflexibility to configuration changes

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent applies universality by designing the set of offset indicators to be independent of specific SPS configurations and TDD frame structures. The same set of offset indicators can be used across different SPS periodicities and TDD configurations, making the HARQ-ACK timing mechanism universally applicable and highly adaptable to configuration changes while maintaining ease of operation through a unified approach.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3866378B1First apparatus, method to operate a first apparatus, second apparatus, method to operate a second apparatus

Publication Date: 2025.10.29 NOKIA TECHNOLOGIES OY

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AI summary

There is provided a method for operating a first apparatus, the method comprises: determining a feedback information for data received via a semi-persistent-scheduled radio resource; mapping the semi-persistent-scheduled downlink radio resource to a radio resource in dependence on at least one of a plurality of offset indicators; and transmitting, if the mapping was successful, the feedback information for the data via the mapped radio resource.